Effect of extrusion cooking on physical properties: A review

Abstract

Extrusion cooking is very important process in food snacks industries to produce the wide range of products. During extrusion cooking, modification in the structure of raw materials such as starch gelatinization, protein denaturation, complex formation between amylose and lipids, degradation reactions of vitamins, pigments etc occurred. Small variations in processing conditions affect process variables and product quality. Extruded snack product’s quality depends on type of extruder, screw configuration, feed moisture, screw speed, feed rate and operational temperature. Effect of extrusion cooking on physical properties covered in this review. Observations found by many researchers that bulk density of extrudates increased with moisture content and feed blends and decreased with increase in temperature. Barrel temperature, feed moisture and blend ratio showed the significant effect on sectional expansion index, specific length, WAI and WSI of extrudates. It was concluded that physical properties of extrudates varied by operational conditions of extruder and process parameters.